Chad provides a lesson on the classification and structures of solids. Amorphous solids are briefly defined before a discussion of crystalline solids with cubic unit cells including Simple Cubic (aka Primitive Cubic), Body-Centered Cubic (BCC), and Face-Centered Cubic (FCC). In these three types of cubic unit cells, the positions occupied by the atoms, the number of atoms per unit cell, the coordination number, and the packing efficiency are all compared and contrasted. A brief discussion of close-packing of spheres is included with a comparison of Hexagonal Close-Packing and Cubic Close-Packing structures follows (HCP vs CCP).
The lesson is concluded with a discussion of the bonding in four different types of solids and how this affects their melting points. Molecular solids are held together by relatively weak intermolecular forces and therefore tend to have relatively low melting points. In contrast, Network Covalent solids and Ionic solids are held together by covalent and ionic bonds respectively and typically have significantly higher melting points. Finally, Metallic solids are held together by metallic bonding. A wide range of strengths are possible in metallic bonding and is related to the number of valence electrons and the number of electrons available for bonding, and therefore the melting points of metals can vary greatly.
I've embedded this playlist as a course on my website with all the lessons organized by chapter in a collapsible menu and much of the content from the study guide included on the page. Check this lesson out at www.chadsprep.com/chads-gener...
If you want all my study guides, quizzes, final exam reviews, and practice exams, check out my General Chemistry Master Course (free trial available) at www.chadsprep.com/genchem-you...
00:00 Lesson Introduction
01:00 Simple Cubic, Body-Centered Cubic, and Face-Centered Cubic Unit Cells
16:12 Close-Packing of Spheres
20:58 Bonding in Solids
www.chadsprep.com/
courses.chadsprep.com/pages/p...